Timing mechanism



Nov. 10, 1964 w. c. MONDAY TIMING MECHANISM 4 Sheets-Sheet 1 Filed July16, 1962 INVENTOR. William 6. Monday Nov. 10, 1964 w. c. MONDAY3,156,351

TIMING MECHANISM Filed July 16, 1962 4 Sheets-Sheet 2 IN V EN TOR.

William 6. Monday BY A fforney Nov. 10, 1964 w. c. MONDAY 3,156,351

TIMING MECHANISM Filed July 16, 1962 4 Sheets-Sheet 3 IN V EN To R.William C. Manda) Affa y Nov. 10, 1964 w. c. MONDAY 3,156,851

TIMING MECHANISM Filed July 16, 1962 4 Sheets-Sheet 4 c- /6 T as c\ I[76 X Normal/y 2 7.9L. Z? Otf Load I Power 1 J\) Power 4: I (S -23Normal/y 89b p54 0n Load I Operating \f2/ 1 L Power l Channel I Normal/yc 36 0n Load v 8 83 -I 82 x) 79 ower 20 Normal/y O\) Power 76 I 89b 2;Operating I 2/ Power Channel I Fig 4 INVEN TOR.

William 6. Mon do y M Q. Attorney United States Patent 3,156,851 TIMINGltlECHANlSM Willi m C. Monday, Albuquerque, N. Mere, assignor, by mesneassignments, to the United States of America as represented by theUnited States Atomic Energy Commission Filed .luly 16, 1962, Ser. No.210,271 8 Claims. (Cl. 317-157) The present invention relates generallyto timing means, and more particularly to a timing mechanism capable ofelfecting multiple switch actuations at or near the end of a pre-setperiod of time.

In the prior art, for example, in connection with missile propulsion orcontrol systems, there has existed for some time a problem of providinga relatively simple and highly accurate timing mechanism capable ofbeing operated for various settable time periods with multiple switchactuations at the end of the set time. This problem has been furthercomplicated by the fact that in many instances actuation of the multipleswitches should be spaced apart from each other by a predeterminedperiod of time. For example, it is often desirable in the propellantsupplying system of a rocket motor to have the fuel enter the combustionzone immediately before the admission of the oxidizer or, whenpressurizing the propellant tanks, to permit the pressurizing medium topressurize the tanks for a given time prior to the opening of the valvefor admitting the propellant to the combustion zone.

The present invention aims to overcome problems or difiiculties such asthe above by providing new and improved means of relatively simple andinexpensive construction which is adapted to provide a timing operationcapable of being readily pre-set to function by actuating switches atthe end of any preselected time period chosen from a wide range ofpossible time settings. The invention further contemplates the provisionof means for providing spaced apart switch actuations at preselectedtime intervals near or at the end of the timing cycle.

An object of the present invention is to provide a new and improvedtiming mechanism capable of being preset to operate for a given timeperiod with multiple switch actuations near or at the end of the settime.

Another object of the present invention is to provide a new and improvedtiming mechanism of relatively simple and inexpensive construction.

Another object of the present invention is to provide a double tripelement arrangement and a differential gearing assembly for attainingthe desired timing period.

A further object of the present invention is to provide reset means forreturning the timing mechanism to a zero or initial setting uponcompletion of the switch actua tions.

A still further object of the present invention is to provide a timingsystem with a pair of internally coupled timing devices for providingback-up means.

Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description. The preferred embodiment illustrated isnot intended to be exhaustive nor to limit the invention to the preciseform disclosed. It is chosen and described in order to best explain theprinciples of the invention and their application in practical use tothereby enable others skilled in the art to best utilize the inventionin various embodiice ments and modifications as are best adapted to theparticular use contemplated.

In the accompanying drawings:

FIG. 1 is a top plan view of a timer housing containing a pair ofinternally coupled timing channels of the present invention with theelectrical circuit removed from one of the timing channels for clarityof illustration;

' FIG. 2 is an exploded schematic perspective view, partly cut away, ofthe gearing arrangement in the timing mechanism of the presentinvention, with the time setting means shown positioned above the geartrain for clarity of illustration;

FlG. 3a is an end view of the present device illustrating the tripelement configurations, the trip element follower, and the microswitcharrangement with the trip element follower engaging a non-microswitchopening portion of the intermediate trip element;

FIG. 3b is a view similar to the view in FIG. 3a, but illustrating thetrip element follower engaging the first step in the intermediate tripelement for opening the contacts on a first set of microswitches;

FIG. 3c is a view similar to the View in FIG. 3a, but illustrating thetrip element follower engaging the third step of the intermediate tripelement for closing a third set of microswitches;

FIG. 4 shows a diagrammatic representation of an electrical circuit thatmay be utilized to internally couple a pair of timing channels of thepresent invention;

FIG. 5a is a plan view of a reset microswitch and actuating sprocketshowing the microswitch in an open position; and

FIG. 5b is a view similar to FIG. 5a, but showing the microswitch in aclosed position.

Described generally, a timing channel or device of the present inventioncomprises (FIGS. 1 and 2) a substantially constant speed electricalmotor 10 including a speed reduction gearing mechanism 11 for rotatingan output shaft 12, a gear 13 and a pair of integral trip elements 15and 16 at a constant low speed or number of revolutions per minute(r.p.m.). A differential gearing assembly surrounding the output shaft12 is driven by the output shaft gear 13 for turning a trip element 17at an rpm. substantially less than the rpm. of trip element 15. Tripelement 17 may be provided with a single large slot 18 and be attachedto the differential gearing mechanism adjacent to trip element A tripelement fol lower 25 (FIG. 3) having associated therewith microswitchesor other similar miniature switches 21, 22, 23 is adapted to engageappropriate steps in trip element 15 and slot 13 in trip element 17 whensuch steps and slot are each in alignment with the trip element followerso as to sequentially actuate the microswitches. An adjustable timesetting means indicated generally at 25 (PEG. 2), may be coupled to thedifferential gearing assembly for initially positioning trip element 17,thus providing a predetermined time period which must elapse before theslot 18 in trip element 17 and the steps in trip element 15 are each inalignment adjacent the trip element follower 28 so as to permit thelatter to engage the steps and slot and actuate the microswitches.

Described in greater detail and referring in particular to FIGS. l-3c apair of timing devices or channels indicated generally at 26 and 27 maybe positioned and secured in a housing 28 by any suitable means. Eachtiming device may comprise a constant speed electrical motor 10 coupledthrough reduction gearing 11 to an output shaft 12 which has a pair oftrip elements 15 and 16 secured thereto and shown adjacent the distalend thereof. T he motor 16 and the reduction gearing 11 may be of anysuitable type, such as, for example, a 28 volt DC. motor operating at12,600 rpm. and an integral speed 7:? reducing assembly for providing anoutput shaft speed of two rpm. Both units are manufactured by GlobeManufacturing Company, Dayton, Ohio. Trip element 15, which is normallythe larger of the two, may be provided with a plurality of progressivelydeeper or deepening steps 30, 311 and 32 respectively, about a portionof its periphery. The circumferential spacing between the respectivesteps is a feature of the present invention which will be discussed indetail below. Assuming clockwise rotation of the shaft 12, the stepsprogressively deepen in the opposite or counterclockwise direction so asto permit the incremental engagement of the trip element follower 26with each step as will be described. While a pair of oppositely disposedtiming devices or channels are shown in the housing (FIG. 1) it will beclear that any suitable number and arrangement of timing devices may beused. I

Gear 13, which may be fixed in any suitable manner to the shaft 12adjacent the reduction gearing ll, drives the ditferential gearingassembly, which may comprise gear train 34, 3 5, 36, 3'7, 3% and 39.Gears 36 and 37 may be integral and along with gear 39, which may bedisposed on the inner surface of cup-like member 4%), may be positionedabout the shaft 12 with suitable low friction hearing means 41 and t2placed 'therebetween so as to permit such gears to be freely rotatableon the shaft 12. Positioned about the shaft 12 on low friction bearingmeans 43 and intermediate gears 36 and 39 is a selectively rotatablegear housing t4 having a centrally disposed counterbore 45 and arecessed or stepped outer portion 4-5. Gear 38 is adapted to berotatably attached on a suitable shaft to a sidewall of the housing 44and be so positioned within the counterbore 4-5 as to permit a portionof the gear 38 to extend outwardly through a slot in the stepped portion46.

When the gears 37, 33 and 39 are in an operative relationship with eachother (FIG. 1), they form a planetary gearing system, i.e., the gear 37acts as the sun gear and is positioned within the gear housingcounterbore 45 where it engages one side of planet gear 33 while thering gear 39 surrounds the gear housing recess 46 and engages theexposed portion of the gear 33. This planetary gearing system providesfor selective rotation of gear housing 44 as will be described below.

The differential gearing assembly provides the gear 39 with asubstantial speed reduction in the opposite or counterclockwisedirection to that of the output shaft 12. Therefore, trip element 17,which may be provided with a single slot 18 and be integral with thecup-like member dill, rotates in the opposite direction to and at a ratesub stantially slower than trip element 15, thus permitting theselectable actuation of the'microswitches by the trip element follower2t Any desired number of speed ratios may be used between the oppositelyrotating trip elements 15 and 17, such as, for example, if the shaft 12has a constant rotational speed of two rpm. and if the speed reductionthrough the differential gearing assembly rotates the trip element 17 atone-tenth the speed of theshaft 12, then this arrangement, due to theinitial trip element settingsand the circumferential displacement andwidth of slot 1%,

permits a maximum rotation of eight revolutions of trip element 15before the slot 118 in trip element 17 and the steps ltd-32; are inalignment Where the trip clement follower 20 can engage the steps andthe slot. The width of slot 18 may be such that with-the sample ratiothe trip element 15 rotates one revolution While trip element 1'7rotates the portion of a revolution equal to the width of the slot 18.Theahove speed ratio example may provide for eight separate timesettings spaced apart from each other by a thirty-second time period.

To provide means for selecting the desired time setting, aselectivelyadjustable dial mechanism may be coupled to the differential gearingassembly through a'pair of bevel gears 48 and 49 and gear 50. Gear 59,which engages matching gear teeth on the outermost peripheral portion ofthe gear housing 44, may then rotate housing 44 in either direction dueto the planetary gearing arrangement of gears Iii-3% which permits gear38 to Walk on gear 37 while rotating gear 39 and trip element 17. Thedial mechanism 25'comprises a cover 52 having a small window 53 thereinand which may be suitably secured to the housing 28 in any desiredlocation, such as the underside of the housing 28 in FIG. 1. A dial 54having a selective numerical time scale indicated on its surface andwhich may be coupled to bevel gear 48 through shaft 56, is placed underthe cover 52 so that only one numeral at any given time is visiblethrough the window 53 and that being the numeral indicative of the timesetting selected for the microswitch actuation.

To set the timing device for microswitch operation at or near the end ofa predetermined timing period, the dial 54 may be rotated until thedesired numeral or other time identifying means is visible under theWindow 53. The rotary movement of the dial 54 rotates shaft 56 and bevelgears 48 and 49 which in turn effects the rotary movement of gearhousing 4-dcausing the gear 38 to rotate gear 39 and position the tripelement slot 1% at such a location with respect to the trip elementfollower 20 that it takes a time period equal to the preset time periodbefore the slot 18 aligns with the trip element follower 2t) and thesteps in trip element 15. The end of the dial shaft 56 adjacent the dial54 may be provided with a small slot St for accepting the end of a screwdriver or the like which may be used to rotate the dial 54 and set theoperating period for the timing device.

A detent arrangement comprising a notched wheel 55 secured to the dialshaft 56 and a pair of balls 57 continuously urged inwardly by spring 58may be used to hold dial shaft 56 against being undesirably rotated outof the preselected time setting once the setting has been selected. Alsothe detent arrangement facilitates accurate settings of the dial 54 byinitially placing the notched wheel on the dial shaft as so that at eachindicated time setting the balls 57 will be in the wheel notches.

The trip element follower it as best illustrated in FIGS. 3a3c,comprises a main body portion 60 pivotally mounted on shaft 61 and has aspur or lateral projection 62 adapted to engage the steps Cid-3?; andthe slot 18 in trip elements 15 and 17 respectively, and a pair ofmicro- 7 switch actuators 64 and 65, one of which may be positioned in aslot 655 while the other may be positioned in an offset rounded portion63. The riser of each step 3tl-32 may be on an acute angle with steptread for facilitating the engagement of the lateral projection 62. Ahclically wound tension spring 67 may have one end secured to themainportion 6t? in such a manner as to continuously urge the trip elementfollower 24 to pivot about shaft 61 and cause the projection 62 to bearagainst the peripheral surface of both trip elements 15 and 17.

Microswitch actuator 64, which comprises a relatively rigid and straightpiece of metal, may be afiixed to the main body portion 6@ of the tripelement follower by inserting and securing one end of the actuator inthe slot 63 provided in the main body portion adjacent the offsetportion 63. The outer or the exposed end of actuator 64 may be widerthan the end secured Within the slot so as to permit the actuator toclose or open the contacts on two pairs of oppositely disposedmicroswitches 21 and 23 (FIG. 1).

, Microswitch actuator 65, on the other hand, preferably comprises aresilient and curved metal spring member secured at one end in anysuitable manner in the offset A portion 63 adjacent to the uppermostpart of the main body portion 6t while the other end or the exposed endmay be providedwith a small'indenture or the like 69 While the actuators64 and 65 are each shown as having widened exposed end portions forsimultaneously opening or closing contacts on a pair of microswitches(the purpose of which will be described below) it will be clear thatsuch end portions may be of any desired width as to engage any desirednumber of microswitch contacts.

When assembling the timing device of the present invention trip elementsand 37 should be initially positioned in proper relationship with eachother so that the timing period set by the dial is accurate. Thiscorrect assembling position may be attained by providing a small notch7% in the tread of step 32 in trip element 15 and a fiducial mark 71 onthe side of trip element 17. Then alignment of the notch 7t) and themark 7i with the end of the projection 62 (FIG. 3a) will properlyposition each trip element with the trip element follower fill.

The scale used on the dial 54 may be used for determining the locationfor the mark "71, or vice versa, since with a known output shaft speedand a given gear ratio in the differential gearing assembly the distancebetween the mark '71 and the opening to slot 18 is directly proportionalto time. Therefore, if it takes, for example, thirty seconds for thetrip element It? to rotate from the point adjacent the mark 71 to theopening of slot 18, then the first numeral on the scale may be with eachaddi tional numeral being a suitable graduation of thirty.

In order to insure that the selected numeral on the dial 54 correspondsto the operating time or" the device, it may be necessary to providemeans for preventing complete rotation of the dial, since by rotatingthe dial 360 or more the slot 18 in trip element 17 may be improperlypositioned with respect to the projection 62 on the trip elementfollower 2% so as to render the timing device inaccurate. may beattained by providing the dial 54 with a raised wedge shaped portion 72at the point of initial setting and the cover 52 with an inwardlyextending pin or the like (not shown) adjacent to and engaging one sideof the wedge when the latter is in its initial position. Thus, the

ial 54 may be rotated in only one direction at the outset, but oncemoved away from its initial position it may then be rotated in eitherdirection to attain the desired setting. However, in no instance may thedial 54 be rotated a complete revolution or 360 so as to improperlyposition the trip element notch it; with respect to the dial 54.

A second channel 27 or back-up timing device, which may be placed inhousing 23 alongside of the first channel 26 (PEG. 1) may be constructedsimilarly to the first channel and be provided with the same speedratios and trip element configurations. Each channel may then bemechanically coupled to the same time setting means 25 so that thetiming period selected by moving the dial 54 positions the trip elementsof each channel to simultaneously align with its trip element followerprojection at the end of the tirm'ng period. To couple the secondchannel 27 to the time settin means, an additional bevel gear 74, whichfunctions in the same manner as bevel gear 49, may be provided in anengaging relationship with the bevel gear 48 on the dial shaft 56.

After the desired time period has been selected on the dial scale andthe motor it) of each timing device energized, the trip element 17 maybe rotated in a counterclockwise direction by the ditferential gearingassembly and the trip element 15 rotated in a clockwise or oppositedirection by the shaft 12. These oppositely rotating trip elements causethe slot 18 in the trip element 17 and the steps in trip element 15 tomove in opposite directions and eventually into alignment with eachother adjacent the projection 62 on the trip element follower 2%. Thus,when the slot lid is in registry with the projection 62 and the steps ofthe faster rotating trip element 15 move into alignment with the slot13, the projection pivots about the trip element shaft 61 under theinfluence of the Prevention of such undesirable dial rotation spring 67and engages the first step 30 in trip element 15 (FIG. 3b). Thispivoting movement of the trip element follower Ztl lifts the actuator 64and opens a first pair of contacts on microswitches 21 (FIG. 1) forcontrolling the operation of an external circuit. Microswitches 22remain closed at the end of the first trip element pivoting movementsince the resilient actuator is not lifted from the contacts but merelysprings into the offset rounded portion 63 of the trip element follower.As the trip element 15 continues to rotate, the trip element followerprojection 62 moves along the step 30 a predetermined length until step31 aligns with the projection 62 which then permits the trip elementfollower 20 to further pivot (not shown) and lift actuator 65 off thecon tacts of microswitches 22, thus controlling the operation of asecond external circuit. When the trip element 15 has rotatedsufficiently to move step 32 into alignment with the trip elementfollower projection 62 (FIG. 30), the trip element follower 20 againpivots and moves the actuator 64 against the contacts of themicroswitches 23, closing the latter and effecting the operation of anadditional external circuit. The closing of the contacts onmicroswitches 23 may indicate the lapse of the time period selected bythe dial setting or, alternatively, the opening of the first set ofmicroswitch contacts 21 may indicate the end of the selected time periodwith the actuation of microswitches 22 and 23 occurring a predeterminedtime thereafter.

The tread lengths of steps 30 and 31 are each directly proportional totime and may thus be of any desired length necessary to establish asuitable time lag between the consecutive actuations of themicroswitches.

Normally after the actuation of microswitches 23 the need for the timingmechanism is ended and the circuit to the motor ltl may be opened by themicroswitches 23 or in any other desired manner to stop the timingoperation so as to leave the trip element projection 62 within step 32and the microswitches 23 in a closed condition.

When providing a timing device with a back-up system or a second timingdevice, as shown in FIG. 1, it may be desirable to internally couple thetimer operating circuits and the microswitch circuits so that if onetimer fails in its intended function due to some unforeseen condition orif one timer is hindered in its timing cycle, then the other timer maycomplete the timing cycle and operate the microswitches. It may also bedesirable to internally couple both the timer motor operating circuitsso that the completion of the timing cycle by one timing devicesimultaneously opens the circuits to both timer motors.

FIG. 4- schematically illustrates how a pair of separate timing devicesmay be internally coupled so that the circuits of one timing device arecapable of being opened or closed by the other timing device. Variouscomponents of channels I and II are designated by numerals similar tothe numerals used in FIGS. l-3c to indicate like components. The Wiringdiagram shows a duplicatron of external loads or circuits for eachtiming device, thus providing back-up circuits for external use.However, in event only a single set of external circuits is desired forthe timing mechanism the wiring and microswitches associated with theexternal back-up circuit may be omitted, thus omitting one microswitchof each pair of microswitches 21-23.

resser the trip element 15 moves the switch 6d into engagement withswitches 23 and closes the circuit from power source 89a to loads 76 ofboth channels. Thus, as above described, the back-up system includingthe internally coupled circuits provides a fail-safe timing mechanismcapable of performing its intended function through the operation ofeither timing channel.

Upon completion of the timing operation, it may be desired to reuse thetiming mechanism in a subsequent operation and in order to do so thecams should be returned to their original positions. To accomplish thisa reset system may be used such as, for example, one comprising a firstreset m'icroswitch '78 having a spring loaded actuator '79 andpositioned adjacent trip element lie so as to permit the actuator 79 toengage notch 55% in trip element 16 and open the microswitch contact(FIG. 3a). A second reset microswitch 82 may be positioned adjacent togear 36 of the differential gearing system and be provided with a springloaded actuator 83. A pair of dowels or pins 84- (one not shown) extendfrom the side wall of gear 36 and are circumferentially spaced 180 apartfrom each other. Each of these pins $4 is adapted to engage any of aplurality of notches d5 a sprocket 86 (FIG. So) as the gear 36 rotates.The sprocket, which may be rotatably mounted in any suitable manner uponthe timing device, in turn engages the actuator 83 for controlling theoperation of the microswitch. A single enlarged notch 83 in the sprocket86 is adapted to 'e eive the actuator 83 and open the microswitchcontact (FIG. So) while the other notches 85 are to ll f h actuatoracceptance, thus permitting microswitch' 053511- 111g at only oneposition on the sprocket 86 (FIG. 51)). As shown in FIG. 4, the resetmicroswitches 7t; and 82 are arranged in a parallel circuit between apower source 8912, which may have a manually operated switch 90, and themotor it) of the timing device so that if both microswitches 78 and 82are simultaneously opened the circuit between the power source 8% andthe motor 16 will be broken.

The operating power for the motors It loads '75, '76, and the resetmechanisms of both channels is preferably obtained from a single powersource which for convenience and clarity of description and illustrationis shown as rectangles 39, 89a, and $919 in H6. 4. However, if desired,independent power sources may be provided for one or more of the motors,loads, or reset mechanisms.

Gear 36, when using the above described speed ratio for example, mayrotate at one-third the speed of trip element 16, thus sprocket 86 withsiX notches, including the large notch 88, completes a completerevolution for every three revolutions of the gear 336. Therefore, withth sample speed of trip element 37 being one-tenth the speed of tripelement 16, it will complete a full revolution for each full revolutionof sprocket 86. When initially setting the timing device during assemblythe microswitches 7t and 3t? should each be open as shown in FIGS. 3aand 5a respectively. After the completion of a timing operation, themotor lil may be energized by the power source 8% by closing the switch96 so as to rotate gear 36 and the trip element 16. When thetripelements l6 and 17 are returned to their preset or initial position,both microswitches 7d and 32 will open to break the power circuit andstop the motor 1d.

When providing a timing device with a reset circuit as above described,the step 32in trip element 15 should gradually slant outwardly towardsthe trip element p eriphery so as to lift the trip element followerprojection 62 out of notch 13 in trip element 1'7. Also, the notch 18 intrip element 17 should be sufiiciently wide as to prevent the tripelement 1'7 from engaging the trip element follower Zii before thelatter is lifted out of the to the trip element follower means.

ti notch 18, since such engagement maydamage the timing device.

The timing mechanism of the present invention provides numerousadvantages over the timers now in use and could be easily adapted tofunction within many electrical systems where multiple timed switchclosures and reliability are desired. By varying the input speed and/ orthe gear ratios the maximum operating time may be varied from a fewseconds to days with the end time resolution being in the order offour-tenths percent of the total time setting.

As various changes may be made in the form, construction and arrangementof the parts herein without departing from the spirit and scope of theinvention and without sacrificing any of its advantages, it is to beunderstood that all matter herein is to be interpreted as illustrativeand not in a limiting sense.

I claim:

1. A device of the character described comprising in combination a'constant speed driving means having a rotatable output shaft extendingtherefrom, trip element means secured to said shaft, additional tripelement means positioned intermediate the first mentioned trip ele mentmeans and said driving means, means adapted to be driven by said drivingmeans for rotating said additional trip element means in a directionopposite to and at a soced less than said firstmentioned trip elementmeans, switch means disposed adjacent to both of said trip elementmeans, means operatively associated with both of said trip element meansfor actuating said switch means when both of said trip element means arerotated to have a predetermined positional relationship with each other,and means operatively associated with said additional trip element meansfor initially positioning the latter.

2. A timing device comprising in combination a contoured pair ofoppositely rotating means, drive means for rotating said rotating meansat dilierent speeds, a plurality of switch means disposed adjacent tosaid rotating means, actuating means operatively associated with saidrotating means and said switch means for sequentially actuating saidswitch means in response to predetermined contour alignments betweensaid pair of rotating means with each other and with said actuatingmeans, and means operatively associated with a portion of said drivemeans for initially position ng one of said rotating means.

3. A timing device of the character described comprising in combinationa constant speed drive means having speed reduction means and arotatable shaft operatively associated therewith, trip element meansattached to said shaft having an inwardly disposed notch means in aportion of the peripheral surface thereof, gear means secured to saidshaft, a diiierential gearing assembly disposed about said shaftintermediate said trip element means and said gear means and rotated bysaid gear means, said gearing assembly being provided with bearing meansfor free rotation on said shaft, additional trip element means having aslot in the peripheral surface thereof and rotatably positioned on saidshaft adjacent to said first mentioned trip element means and adapte tobe rotated by said gearing assembly in a direction opposite to the firstmentioned trip element means, trip element follower means operativelyassociated with both of said trip element means, switch means positionedadjacent to said trip element follower means and adapted.

to'be actuatcd'by said trip element follower means when the slot andnotch means of both trip element means are rota-ted into alignment withthe trip element follower means and receive the latter, and dial meansoperatively attached to the differential gearing assembly for initiallypositioning the additional trip element means with respect 4. The deviceclaimed in claim 3 means in the first mentioned trip element meanscomprises a plurality of progressively deepening stepped portionswherein the notch with each stepped portion being of predeterminedlength, and wherein said switch means comprises a plurality ofmicroswitches adapted to be sequentially actuated by the trip elementfollower means as the latter sequentially engages the stepped portions.

5. The device claimed in claim 4 wherein the trip element follower meanscomprises a main body portion pivotally mounted on a shaft and includesa lateral projection adapted to engage the slot and the steppedportions, a spring means is secured to the body portion for continuouslyurging the main body portion to pivot and move the projection into theslot and stepped portions, and a pair of microswitch spring loadedactuators is secured to the main body portion.

6. The device claimed in claim 3 wherein said dial means comprises adial shaft having gear means, a rotatable dial having a timing scaleindicated on a surface thereof and aflixed to said shaft, spring loadeddetent means is provided on said shaft intermediate said dial and thegear means on the dial shaft for maintaining the dial in a selectedtiming position, and additional gear means is provided operativelyintermediate the gear means on the dial shaft and the differentialgearing assembly, the difierential gearing assembly includes planetarygearing which permits the dial means to initially rotate the additionaltrip element means in either direction while leaving the notched tripelement means in a stationary position, and wherein the detent means isadapted to normally secure the palentary gearing from rotation aboutsaid rotatable shaft.

7. The device claimed in claim 3 including reset means for returningboth trip element means to an initial preselected position, said resetmeans comprising a further trip element means having a notch therein andsecured to the shaft, a microswitch having an actuator adapted to engagethe notch of said further trip element means, pin means secured to agear in the diiferential gearing assembly, a notched sprocket adapted tobe rotated by said pin means, a second microswitch having an actuatoradapted to engage a notch in said sprocket, and means adapted to effectrotation of said further trip element means and said sprocket until theactuators of each microswitch simultaneously engage the trip elementnotch and said sprocket notch.

8. A timing apparatus of the character described comprising incombination a housing having a plurality of timing devices dispcsedtherein, each device including a pair of counter-rotating means, one ofwhich rotates at a speed slower than the other, switch means operativelyassociated with each pair of counter-rotating means and adpated to beactuated thereby, means common to said devices for initially positioningone of said counterrotating means of each device with respect to theother counter-rotating means of the same device, and circuit meansinterconnecting the switch means of each device, whereby actuation ofswitch means in one of said devices actua-tes said circuit means.

References Qited in the file of this patent UNETED STATES PATENTS2,477,953 Berthiez Aug. 2, 1949 2,975,612 Everard Mar. 21, 19613,001,036 Everard Sept. 19, 1961 FOREIGN PATENTS 916,883 France Aug. 26,194-6

8. A TIMING APPARATUS OF THE CHARACTER DESCRIBED COMPRISING INCOMBINATION A HOUSING HAVING A PLURALITY OF TIMING DEVICES DISPOSEDTHEREIN, EACH DEVICE INCLUDING A PAIR OF COUNTER-ROTATING MEANS, ONE OFWHICH ROTATES AT A SPEED SLOWER THAN THE OTHER, SWITCH MEANS OPERATIVELYASSOCIATED WITH EACH PAIR OF COUNTER-ROTATING MEANS AND ADAPTED TO BEACTUATED THEREBY, MEANS COMMON TO SAID DEVICES FOR INITIALLY POSITIONINGONE OF SAID COUNTER-